The goal of my proposed dissertation research is to integrate smartphone and internet data technologies to develop and validate new methodologies in objectively assessing diet and physical activity patterns and built environment exposures in order to examine the relationships between personal food environment exposures, diets and obesity risk in a susceptible population in a rapidly urbanizing environment where risk transitions are rapidly occurring. This research is highly relevant to the protection of public health as many regions of the world are rapidly urbanizing and are at risk for obesity. Kunming is a prototypical medium-sized city in China, where there is rapid redevelopment and construction of new neighborhoods along the lines of the modernization that has already occurred in eastern coastal cities such as Shanghai and Beijing. These environmental changes are paralleled by rapidly increasing child and adult obesity rates. It is an excellent site for thi research, as it builds upon pilot studies and collaborations with researchers and students at Kunming Medical University that I have developed over the last two years. My research aims are to 1. Assess the citywide differences in food environment in Kunming using Google Maps and field observations; 2. Quantify personal food environment exposures in 264 high school students based on each student's smartphone GPS routes; 3. Record diet patterns using voice-annotated video and physical activities via smartphones, and 4. Assess the relationships between food environment, diet and physical activity patterns and social networks, and their associations with BMI via multivariate modeling.